Support replying to Airbnb Support threads via MCP / Public API

Problem: Hosts using MCP can reply to guest reservation conversations (send-reservation-message) but cannot reply to Airbnb Support threads programmatically. Today those threads can only be answered manually from the Hospitable inbox UI. Requested behaviour: Expose Airbnb Support threads through MCP and the Public API so AI agents / external tooling can read and reply to them, the same way they handle reservation messages. Why it matters: Hosts automating guest comms via MCP hit a dead-end for Airbnb Support messages. Airbnb's API already surfaces these threads to us (we import them into the inbox), so the capability exists on their side. Scope / out of scope: In scope: read + reply on existing Airbnb Support threads. Out of scope: initiating new Airbnb Support threads (not supported by Airbnb).